Apostol, who was in the first group of Philippine students sent to America by Governor William H. Taft, later president and chief justice of the U.S. Supreme Court, was one of the illustrious alumni of Purdue, having received the only honorary degree, master of agriculture, ever awarded by his alma mater. That was in 1921 when he returned to Purdue for the first time since his departure in 1908. Apostol having spent 1920 and 1921 in a tour to various countries to study rice production. Shortly after he went back to Manila he was promoted to the post of under secretary of agriculture.

While in Purdue, Apostol was one of the most prominent students on campus and rose to the post of lieutenant colonel of the cadet corps, being the first and only man from a foreign land to achieve this distinction. He was a member of Scabbard and Blade military fratenity and the Cosmopolitan club. He organized the Purdue Alumni Association in Manila, and was active in sending many Filipinos to Purdue and other American universities.